Showing papers in "Journal of building engineering in 2016"
TL;DR: In this article, the feasibility of incorporating high-quality recycled concrete aggregates in new concrete, providing a recycling option for precast rejects, is investigated and the results of this experimental campaign are benchmarked with other investigations.
Abstract: Sustainability is a pressing concern of the 21st century. Social development in most countries is raising awareness of the needs of future generations and legislation to protect the present and future quality of life. These needs are compelling various sectors, including construction, to find sustainable solutions. This paper investigates the feasibility of incorporating high-quality recycled concrete aggregates in new concrete, providing a recycling option for precast rejects. The massification of recycled aggregate incorporation would decrease the environmental impacts of the concrete industry, for instance due to reduced landfill disposals, less quarry mining and shortened transport distances. The study presented in this paper concerns the material, mechanical, durability and short-term structural behaviour of concrete specimens and structures made with recycled aggregates sourced from high-quality concrete elements. This paper intends to provide a holistic view of the study, from the procurement and crushing process that generated the aggregates to the conclusions of the different experiments performed. The results of this experimental campaign are benchmarked with other investigations and the importance of the quality of the RA is evaluated. This paper concerns the first full-scale experiments made on recycled aggregates concrete structures. Also, some of the tests performed were the first of their type made on recycled aggregates concrete.
169 citations
TL;DR: This paper presents the first Big Data based architecture for construction waste analytics, validated for exploratory analytics of 200,000 waste disposal records from 900 completed projects and revealed that existing waste management software classify the bulk of construction waste as mixed waste, which exposes poor waste data management.
Abstract: In recent times, construction industry is enduring pressure to take drastic steps to minimise waste. Waste intelligence advocates retrospective measures to manage waste after it is produced. Existing waste intelligence based waste management software are fundamentally limited and cannot facilitate stakeholders in controlling wasteful activities. Paradoxically, despite a great amount of effort, the waste being produced by the construction industry is escalating. This undesirable situation motivates a radical change from waste intelligence to waste analytics (in which waste is propose to be tackle proactively right at design through sophisticated big data technologies). This paper highlight that waste minimisation at design (a.k.a. designing-out waste) is data-driven and computationally intensive challenge. The aim of this paper is to propose a Big Data architecture for construction waste analytics. To this end, existing literature on big data technologies is reviewed to identify the critical components of the proposed Big Data based waste analytics architecture. At the crux, graph-based components are used: in particular, a graph database (Neo4J) is adopted to store highly voluminous and diverse datasets. To complement, Spark, a highly resilient graph processing system, is employed. Provision for extensions through Building Information Modelling (BIM) are also considered for synergy and greater adoption. This symbiotic integration of technologies enables a vibrant environment for design exploration and optimisation to tackle construction waste. The main contribution of this paper is that it presents, to the best of our knowledge, the first Big Data based architecture for construction waste analytics. The architecture is validated for exploratory analytics of 200,000 waste disposal records from 900 completed projects. It is revealed that existing waste management software classify the bulk of construction waste as mixed waste, which exposes poor waste data management. The findings of this paper will be of interest, more generally to researchers, who are seeking to develop big data based simulation tools in similar non-trivial applications.
130 citations
TL;DR: In this paper, the authors analyzed the seismic vulnerability of the historical complex of "San Francesco " located in Cagli, Marche Region, Italy, using Finite Element Modelling (FEM) technique, where the nonlinear behaviour of masonry has been taken into account by proper constitutive assumptions.
Abstract: The paper analyzes the seismic vulnerability of the historical complex of “ San Francesco ” located in Cagli, Marche Region, Italy. It provides both advanced 3D modelling with solid elements and equivalent frame modelling. The building is composed of a church and a monastery used as a lower secondary school, and preservation and maintenance of its structural efficiency are of primary importance. The global structural behaviour and dynamic properties of the compound have been evaluated using the Finite Element Modelling (FEM) technique, where the nonlinear behaviour of masonry has been taken into account by proper constitutive assumptions. A sensitivity analysis is done to evaluate the effect of the choice of the control point on the value of seismic risk index, by varying the stiffness of the floors and the effects of different knowledge levels. The aim of the paper is to emphasize the importance of thorough knowledge of historic buildings in order to understand the real seismic behaviour of a structure, to detect common vulnerability of this type of building, the knowledge of which is necessary to design restorations aimed at improving the seismic behaviour of masonry buildings. Some comparisons with the Equivalent Frame Method (EFM) are also presented.
127 citations
TL;DR: In this paper, an attempt was carried out to develop some properties of self-compacted concrete (SCC) by adding waste plastic fibers (WPF) resulting from cutting beverage bottles, whereas other tests were applied on that kind of concrete to study the effect of this type of waste on hardened properties.
Abstract: An attempt was carried out to develop some properties of self-compacted concrete (SCC) by adding waste plastic fibers (WPF) resulting from cutting beverage bottles. Many tests were conducted to investigate the effect of adding WPF on the fresh properties, whereas other tests were applied on that kind of concrete to study the effect of this type of waste on hardened properties. For this reason, different self-compacting concrete mixtures were designed at constant water-to-binder ratio of 0.35 and 490 kg/m3 of binder content. The class F fly ash was replaced with cement as 25% by weight. The eighth designated plastic fiber contents of 0%, 0.25%, 0.5%, 0.75%, 1%, 1.25%, 1.5%, 1.75% and 2% by volume. The workability properties of self-compacting concrete mixtures were performed to slump flow diameter, T50 slump flow simultaneously, V-funnel flow at the same time, and L-box height ratio. The 7, 14 and 28-day compressive strengths of self-compacting concretes were also measured. Moreover, the 7, 14 and 28-day flexural strengths of concretes were also measured. The test results showed that the plastic fibers have adverse effect on the fresh properties of self-compacting concrete and improvement by hardened properties.
126 citations
TL;DR: In this paper, the authors quantify environmental impacts associated with mixing compositions of concrete made of waste materials by using LCA, using various impact assessment methods, according to both EN 15804 and NF P 01-010 standards.
Abstract: Recycled concrete aggregates from demolition constitute one of the largest waste streams within the developed countries. These study aims to quantify environmental impacts associated with mixing compositions of concrete made of waste materials by using LCA. Environmental performances of natural, recycled and mixed 20-mm concrete samples, formulated with the same mechanical strength regarding the functional unit, were evaluated. Eight millimeter concrete samples, formulated with natural or recycled (concrete or terracotta brick) aggregates – with the same volume composition of the granular skeleton for apparent concrete application regarding the functional unit – were also studied. The LCA results are presented using various impact assessment methods, according to both EN 15804 and NF P 01–010 standards. Recycled samples present good environmental behavior, even if recycled materials (sand and aggregates) involve different operations (crushing against extraction, etc.). The terracotta 8-mm concrete sample presents low environmental impacts in comparison with the other 8-mm concrete samples. This sample exhibits a low aggregate density, which decreases transport impacts, and good mechanical strengths, which improves its lifetime.
122 citations
TL;DR: In this article, the use of waste materials (RHA and bagasse ash) for brick production has been attempted and it was observed compressive strength and modulus of rupture decreased with incorporation of RHA and SBA in burnt clay bricks.
Abstract: Burnt clay brick is the commonly used construction material across the world. In most of countries including Pakistan, brick manufacturing is ignorant of modern day improvements and innovations. Utilization of waste materials in manufacturing of clay bricks is not only helpful in disposal of wastes safely but also imparts useful properties to the burnt clay bricks. In this study, the use of waste materials (rice husk ash and bagasse ash) for brick production has been attempted. Clay bricks were prepared incorporating 5% by clay weight of rice husk ash (RHA) and sugarcane bagasse ash (SBA) to investigate the mechanical and durability properties. It was observed compressive strength and modulus of rupture decreased with incorporation of RHA and SBA in burnt clay brick. However, compressive strength and modulus of rupture satisfied the requirements of building bricks according to Pakistan building code and ASTM standard guidelines. Furthermore, clay bricks incorporating RHA and SBA can be potentially used in the production of lighter bricks. Lighter weight of bricks can result in reduction of structural loads and helpful in achieving economy. Test results confirmed the use of clay bricks incorporating RHA and SBA as moderate weather resistive bricks. Moreover, resistance against efflorescence was improved after incorporating RHA and SBA. The microstructure was examined by scanning electron microscopy (SEM) and found that burnt clay bricks incorporating RHA and SBA were more porous than burnt clay bricks. Based on this study, it can be concluded that the addition of RHA and SBA is not only helpful in controlling environmental pollution but also results into a more sustainable and economical construction.
117 citations
TL;DR: In this article, the authors examined the cultural profile of the construction industry to understand cultural factors contributing to waste intensiveness of the industry, as well as those preventing effectiveness of existing waste management strategies.
Abstract: Owing to its contribution of largest portion of landfill wastes and consumption of about half of mineral resources excavated from nature, construction industry has been pressed to improve its sustainability. Despite an adoption of several waste management strategies, and introduction of various legislative measures, reducing waste generated by the industry remains challenging. In order to understand cultural factors contributing to waste intensiveness of the industry, as well as those preventing effectiveness of existing waste management strategies, this study examines cultural profile of construction industry. Drawing on four focus group discussions with industry experts, the study employs phenomenological approach to explore waste inducing cultural factors.
Combining findings from phenomenological research with extant literatures, the study suggests that in order to reduce waste intensiveness of the construction industry, five waste inducing cultural factors need to be changed. These include (i) “make-do” understanding that usually result in “make-do waste” (ii) non-collaborative culture, which results in reworks and other forms of wasteful activities (iii) blame culture, which encourages shifting of waste preventive responsibilities between designers and contractors, (iv) culture of waste behaviour, which encourages belief in waste inevitability, and (v) conservatism, which hinders diffusion of innovation across the industry. Changing these sets of cultural and behavioural activities is not only important for engendering waste management practices; they are requisite for effectiveness of existing strategies. Improvement in the identified areas is also required for overall improvement and general resource efficiency of the construction industry. Thus, this paper advocates cultural shift as a means of reducing waste landfilled by the construction industry, thereby enhancing sustainability and profitability of the industry.
103 citations
TL;DR: In this paper, the authors present a literature review on the LCAs for phase change materials (PCM) incorporating structures, in order to present the current state of the art, the research challenges, and what is to be looked forward in the near future.
Abstract: The environmental impact of Phase Change Materials (PCMs) incorporated in building envelopes is an extensively studied area of research, typically assessed by employing a Life Cycle Assessment (LCA) approach. The aim of this paper is to conduct a literature review on the LCAs for PCM- incorporating structures, in order to present the current state of the art, the research challenges, and what is to be looked forward in the near future. A brief recap on the development of PCMs and the fundamentals of their operation in buildings is presented. The principles of LCA, according to the International Standards, and the suitability of its application on PCMs are also discussed. This study presents some significant findings regarding the application of LCA to PCM- incorporated building systems. In particular it has been shown that there is consistency among the findings of the studies, however the findings were found to depend on the goal and scope definition of each LCA. Additionally, taking into consideration all the life- cycle phases of PCM- incorporated building constructions, they were found to be more environmental- friendly compared to other conventional thermal insulating materials.
88 citations
TL;DR: A review of the past/recent work on various aerodynamic mitigation techniques developed for reducing wind loads on buildings by modifying their shapes and/or adding simple architectural elements can be found in this paper.
Abstract: Usually the design of the external shape and orientation of buildings is driven by architectural considerations, functional requirements and site limitations, rather than by aerodynamic considerations. This, most of the times, results in structures becoming bluff bodies characterized by high wind-structure interaction induced loads. These effects can be significantly reduced through novel aerodynamic mitigation techniques and optimal aerodynamic shape design procedures. This paper reviews the past/recent work on various aerodynamic mitigation techniques developed for reducing wind loads on buildings by modifying their shapes and/or adding simple architectural elements. Aerodynamic mitigation techniques applicable to low-rise and high-rise buildings have been reviewed. In addition, aerodynamic shape optimization techniques for reducing wind loads on tall buildings are presented and the suitability and challenges of using Computational Fluids Dynamics (CFD) for this application are discussed. An overview of the optimization techniques namely gradient based methods and non-gradient based methods are presented. It is expected that this research can ignite an interest in using aerodynamic shapes and consideration of the structures’ shape, in terms of wind performance, early in the design process. This paper also serves as a source for various techniques that can be used for reducing wind loads on buildings.
84 citations
TL;DR: In this article, white rice husk ash was used for producing sodium waterglass with different molar ratios SiO 2 /Na 2 O (0.31, 0.47; 0.62, 0., 0.78 and 0.25) and then used to synthesize metakaolin-based geopolymer cements.
Abstract: Rice husk from source in Cameroon was leached in HCl (5 M) to remove the most of metallic ingredients and then calcined at 600 °C in order to produce white rice husk ash. This white ash were applied for producing sodium waterglass with different molar ratios SiO 2 /Na 2 O (0.31; 0.47; 0.62; 0.78; 0.93; 1.09 and 1.25) and then used to synthesize metakaolin-based geopolymer cements. The obtained white rice husk ash shows the loss of crystalline mineral and reveals high amorphous silica with quartz as impurity. Geopolymers GPi (i varying from 1 to 7) were obtained using different synthesis sodium waterglass (NWG) with a mass ratio NWG/MK=0.87. It could be observed that the 28 days compressive strength (4/5/7/9/32/34/36 MPa) increase with increasing the molar ratios SiO 2 /Na 2 O defined in this work in the course GP1/GP2/GP3/GP4/GP5/GP6/GP7. The micrographs show the formation of more geopolymer gels when the molar ratios SiO 2 /Na 2 O in alkaline activators are between 0.93 and 1.25. Sodium waterglass from white rice husk ash proved to be an effective alkaline activator in geopolymers preparation. It can be concluded that it is possible to replace quartz sand and sodium carbonate which is responsible to greenhouse gas emitted during the production of commercial sodium silicate solution by using rice husk as silica sources.
84 citations
TL;DR: In this article, the effects of sodium and potassium based activators on compressive strength and physical changes of class F fly ash geopolymer exposed to elevated temperatures were presented and compared.
Abstract: This paper presents the effects of sodium and potassium based activators on compressive strengths and physical changes of class F fly ash geopolymer exposed to elevated temperatures. Samples were heated at 200 °C, 400 °C, 600 °C and 800 °C to evaluate the residual compressive strength after 28 days of curing. The fly ash geopolymer were synthesized with combined sodium silicate and sodium hydroxide solutions and potassium silicate and potassium hydroxide solutions by varying mass ratios of Na 2SiO3/NaOH and K2SiO3/KOH of 2, 2.5 and 3. Results show significant improvement is compressive strength in the case of Na2SiO3/NaOH ratio of 3 than 2 and 2.5, where the residual compressive strengths are increased up to 600 °C. Better results on the geopolymer synthesized with potassium based activators are obtained where the residual compressive strength up to 600 °C are much higher than their sodium based counterparts. It is also found that the fly ash geopolymer synthesized with potassium based activators is more stable at elevated temperatures than its sodium based counterparts in terms of higher residual compressive strengths, lower mass loss, lower volumetric shrinkage and lower cracking damage. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) results of sodium and potassium activator synthesized fly ash geopolymer also corresponds to the measured residual compressive strengths.
TL;DR: In this article, an experimental investigation of air flow and thermal management of data center buildings is conducted for different arrangements of cold aisles containments, including free open cold aisle, semi-enclosed cold aisle and full enclosed cold aisle.
Abstract: Cold aisles containments are used in data centers buildings to improve the thermal managements of the IT servers. In the present study, an experimental investigation of air flow and thermal management of data center buildings is conducted for different arrangements of cold aisles containments. A scaled physical model simulating real data centers is designed using scale modeling theory and constructed for the sake of the present experimental work. The data center scaled model accommodate a row of three racks; each rack included four servers for testing purposes. Three arrangements of cold aisles are tested: (i) free open cold aisle, (ii) semi-enclosed cold aisles where the aisles are enclosed from the sides, and (iii) full enclosed cold aisles, where the aisles are enclosed from sides and top. Front and rear racks temperatures profile, servers temperatures and performance measuring parameters Supply/Return Heat Index (SHI/RHI) are used to evaluate the thermal management/performance of the data centers racks. Experiments were conducted at different racks power densities. The results showed that (i) increasing data centers power density and supplied air flow rates improves SHI but increases servers temperature, (ii) using semi-enclosed cold aisles relatively improve the thermal performance of the data centers, (iii) using full enclosed cold aisles dramatically improve the thermal performance of the data center servers, and (vi) the percentage of enhancement in data centers performance due to using cold aisle containments dramatically increases with increasing the power density.
TL;DR: In this article, the authors present a method involving on-site measurements and dynamic simulation to evaluate refurbishment solutions of an extended and complex building of great artistic and historical value, Villa Mondragone, located in the Colli Albani area and property of the University of Rome Tor Vergata.
Abstract: The paper presents a method involving on-site measurements and dynamic simulation to evaluate refurbishment solutions of an extended and complex building of great artistic and historical value, Villa Mondragone , located in the Colli Albani area and property of the University of Rome Tor Vergata . The approach has been successfully applied to a historic building of great construction complexity that was built during centuries, superimposing different construction technologies and styles. Masonry characteristics of ancient buildings are often hard to find and in situ measurements of thermal parameters ( U -values) are time consuming, especially for large estates with structures of various superimposed ages as the case of Villa Mondragone . The paper demonstrates how a specific calibration of the dynamic model using only indoor temperature measurements can overcome this problem. The model was used to evaluate the energy performance of the actual use of the Villa and two possible cases of intervention. An improvement of approximately 40% in the energy demand has been evaluated adopting refurbishment solutions without impact on the historical value of the building. The model could be used also in the future to evaluate various refurbishment solutions not only regarding the envelope but also the plant and its use.
TL;DR: In this article, three different possible scenarios based on prime mover capacity are introduced and an economical study on each scenario is conducted to determine the optimal PMO capacity for this building with regard to the availability of each alternative.
Abstract: Combined cooling, heating and power (CCHP) systems have attracted substantial interests during past decades as they can offer higher thermal efficiency compared to single power generation systems. This paper mainly aims to shed light on applying a CCHP system for a commercial and office buildings in Tehran, Iran. To achieve this, one of the most critical parameters on the CCHP system performance that is the choice of equipment capacity is considered. In this regard, three different possible scenarios based on prime mover capacity are introduced and an economical study on each scenario is conducted to determine the optimal prime mover capacity for this building with regard to the availability of each alternative. Finally, the reduction of pollutant emissions due to applying CCHP system for this commercial and office building is studied and the relevant results are reported. Regarding the current energy costs in Iran, optimal capacity of prime mover requires to be designed as equal electricity generation capacities (based on peak load) and electric demand of the building. In addition, from an environmental perspective, it is concluded that 1,071,428 USD is dictated on community in term of natural gas and domestic use of electricity in this commercial building.
TL;DR: In this article, a case study based on an industrial precast structure located in Italy is presented to investigate the influence of different variables on the connection behavior, as well as the results of different safety assessment approaches.
Abstract: A key aspect in determining the seismic performance of industrial Precast Structures (PS) are the connections between precast elements. The main issue is the capacity of beam-column connections to allow relative displacements without losing beam seating, and to transfer lateral horizontal forces from the beam to the column, without losing load carrying capacity. Referring to a case study based on an industrial PS located in Italy, this work critically investigates the influence of different variables on the connection behaviour, as well as the results of the different safety assessment approaches. Attention has been paid to provide a comparison between different (linear and nonlinear, static and dynamic) analyses with both lumped and diffused nonlinear models. The analyses highlight the importance of the connection between members in the seismic upgrade of existing PS, and the minor role of the mechanical slenderness of the column when considering weak connections.
TL;DR: In this paper, the authors present an overview of previous studies carried out on the use of the previous wastes as a partial or full of natural fine aggregate replacement in traditional mortar/concrete mixtures based on Portland cement (PC).
Abstract: In the last 15 years, the worldwide consumption of natural sand as fine aggregate in mortar/concrete production is very high and many developing countries have encountered some problems in the supply of natural sand in order to meet the increasing demands of construction development. In many countries there is a shortage of natural sand that is suitable for construction. On the other hand, disposal of wastes such as fly ash (FA), bottom ash (BA) and agricultural wastes can be considered as the major environmental challenges. This challenge continues to increase with the increase of these wastes. Therefore, studies have been carried out to find suitable solutions of the shortage of natural sand and the huge increasing in the wastes disposal. One logical option to solve this problem is employing these materials as a part of fine aggregate instead of natural one in mortar/concrete. This paper presents an overview of the previous studies carried out on the use of the previous wastes as a partial or full of natural fine aggregate replacement in traditional mortar/concrete mixtures based on Portland cement (PC). Other cementitious material such as ground basaltic pumice and metakaolin (MK), which can replace part or full of natural fine aggregate was also included. Fresh properties, hardened properties and durability of mortar/concrete containing these waste/cementitious materials as natural fine aggregate replacement have been reviewed.
TL;DR: In this study, a HVAC system had been modeled using MATLAB simulation software that had been developed using a fuzzy controlling system and radial basis function (RBF) model of artificial neural network (ANN) as a predictive control system to find the best performance.
Abstract: Heating, ventilating and air conditioning (HVAC) systems are used in buildings, industry and agriculture to provide thermal and humidity comfort. Modeling of HVAC system can help to design precise controlling systems. In this study, a HVAC system had been modeled using MATLAB simulation software that had been developed using a fuzzy controlling system and radial basis function (RBF) model of artificial neural network (ANN) as a predictive control system. Results of the modeled systems were extracted and compared with actual system. In order to compare results of the modeled and actual systems, comparing parameters, such as mean absolute error (MAE), root mean square error (RMSE), mean absolute percentage/relative error (MAPE) and coefficient of Pearson correlation (r) were applied. The results indicated that, the modeled systems was accurately controlling the system and the difference between real and modeled system was also close. In the results as a whole, the predictive controller (RBF network) has the best performance compared to fuzzy model.
TL;DR: In this paper, the authors presented the results of an experimental and analytical investigation of a total of six precast foamed concrete sandwich panels (PFCSPs) as one-way acting slabs tested under flexural loads.
Abstract: This paper presents the results of an experimental and analytical investigation of a total of six precast foamed concrete sandwich panels (PFCSPs) as one-way acting slabs tested under flexural loads. Foamed concrete of 25.73 MPa was used to produce the PFCSP concrete wythes. The results obtained from the tests have been discussed in terms of ultimate flexural strength capacity, moment-vertical deflection profile, load–strain relationship, strain variation across the slab depth, influence of aspect ratio, cracking patterns, and ultimate flexural load at failure. An analytical study of finite element analysis (FEA) as a one-way slab model was then conducted. The increase in aspect ratio (L/d) from 18.33 to 26.67 shows a reduction of 50% and 69.6% on the ultimate flexural strength capacity as obtained experimentally and in FEA models, respectively. Theoretical analyses on the extremes of fully composite and non-composite actions were also determined. The experimental results showed that cracking patterns were observed in one direction only, similar to those reported on a reinforced concrete solid slab, as well as precast concrete sandwich panels, when both concrete wythes act in a single composite manner. The experimental results were compared with FEA model data, and a significant degree of accuracy was obtained. Therefore, the PFCSP slab can serve as an alternative to the normal concrete slab system in buildings.
TL;DR: In this paper, the authors focused on the assessment of the hygrothermal performance of a straw bale house in the Picardie region of France, where the house was built using a wooden load bearing frame filled with straw bales.
Abstract: This paper focuses on the assessment of the hygrothermal performance of a straw bale house in the Picardie, a region of France. The house was built using a wooden load bearing frame filled with straw bales. Laboratory and in situ tests were carried out in this study. In the first part, the thermal conductivity of straw bales was measured in relation to the orientation of the straw fibers. The thermal resistance of a wall built in the laboratory, respecting the real construction parameters, was assessed. The obtained U-value was compared to those of different walls used in civil field engineering. The second part of this paper continues with an assessment of the hygrothermal performance of a real straw bale house. Temperature and relative humidity measurements were recorded during more than one year, using sensors that were placed in indoors and outdoors, and at various depths of the walls and floors. Finally, this paper is completed by a dynamic thermal simulation of the house, based on experimental laboratory investigations. During winter the simulated heating requirements are estimated at 59 kW h/m2. Moreover, the simulation under summer conditions shows the major influence of the building envelope on the thermal comfort. Thus, straw bale walls seems to provide significant thermal inertia in summer.
TL;DR: In this paper, the structural upgrade of a public school building, which did not guarantee safety against collapse under gravity loads and which had been designed ignoring seismic actions, was presented, taking full advantage of the properties, capabilities and opportunities afforded by steel, which was used in a variety of forms and functions.
Abstract: This paper presents the structural upgrade of a public school building, which did not guarantee safety against collapse under gravity loads and which had been designed ignoring seismic actions. The design of the upgrade took full advantage of the properties, capabilities and opportunities afforded by steel, which was used in a variety of forms and functions — namely, cold-formed members, thin-walled sections, welded elements, steel-concrete horizontal and vertical structures. The activity presented here did not use numerical calculation as a means of structural design. The multifarious roles that steel can play make steelwork particularly suited to conservation and upgrade of twentieth century architecture, especially seminal reinforced concrete buildings.
TL;DR: In this paper, a series of compaction tests were carried out for studying the compaction characteristics of the treated coir fibres and pond ash of 0.5-1.5% and 10-30% were added to the stabilized cement (2% and 4%) clayey soil.
Abstract: In a comprehensive laboratory study, different tests namely, standard Proctor tests, unconfined compressive strength (UCS) and split tensile strength (STS) tests were performed for evaluating the compaction and strength behaviour of the cement-stabilized, and sodium hydroxide treated coir fibre reinforced clay-pond ash mixtures. The treated coir fibres and pond ash of 0.5–1.5% and 10–30%, respectively, were added to the stabilized cement (2% and 4%) clayey soil. A series of compaction tests were carried out for studying the compaction characteristics. The cylindrical specimens of dimension 38.1 and 76.2 mm were prepared at desired densities and cured for 7, 14, and 28 days, after which they were, subjected to a series of unconfined compressive strength and split tensile strength tests. The investigation showed that the dry unit weight of the mixtures decreases and water content increases with the addition of pond ash and fibres. The inclusion of fibres and pond ash in the cementitious clay caused an increase in the unconfined compressive strength, split tensile strength and axial strain at failure. Compared with the clayey soil, the incorporation of pond ash (10%) and treated coir fibres (1%) in the cement-stabilized clay with 4% cement content improved the unconfined compressive strength and split tensile strength, i.e. 3.72 and 3.83 times growth in unconfined compressive strength and split strength respectively. The incorporation of treated coir fibre reduced the stiffness, rate of loss of post-peak strength and changed the behaviour of the composite from brittle to ductile.
TL;DR: A 3D-CFD investigation of airflow, temperature distribution and thermal comfort in high rise ceiling theaters air conditioned with underfloor air distribution (UFAD) system is presented for different operating and geometric conditions as discussed by the authors.
Abstract: A 3D-CFD investigation of airflow, temperature distribution and thermal comfort in high rise ceiling theaters air conditioned with underfloor air distribution (UFAD) system is presented for different operating and geometric conditions. Numerical simulations are implemented, using a commercial CFD package (Fluent 6.3), to understand the effects of supply air temperature, supply air velocity, space height and number of supply air diffusers on the performance of the air conditioning system and thermal comfort. For UFAD system evaluation, the traditional overhead mixing air distribution (OHAD) system are also modelled and compared with the UFAD system. The results showed that (i) the used numerical technique could accurately predict the airflow and temperature distribution in the high rise conditioned space, (ii) UFAD system is capable of creating smaller vertical variations of air temperature and a more comfortable environment and energy saving than OHAD system, (iii) the supply air velocity and temperature, number of diffusers and height of the space have a significant impact on thermal comfort, (iv) the optimum system performance and thermal comfort obtained at 18 °C supply air temperature, 0.8 m/s supply air velocity and proper numbers and distributions of supply diffusers, (v) the percentage of energy saving due to using UFAD system increases with increasing the theater height. The simulation results are validated with the available experimental data and good agreement are obtained.
TL;DR: In this paper, the feasibility of utilizing co-combustion fly ashes for the production of eco-friendly fired bricks was studied, and the effect of fly ash with high replacing ratio (from 0 to 80%) of clay on properties of bricks was analyzed.
Abstract: This paper studies the feasibility of utilizing co-combustion fly ashes for the production of eco-friendly fired bricks. The fly ashes from co-combustion of coal and pet coke in a Spanish Power Plant were used as raw material to replace clay to make fired bricks. The effect of fly ash with high replacing ratio (from 0 to 80%) of clay on properties of bricks was analysed. The specimens, cylinders with 32.5 mm diameter and 50 mm length, were manufactured by compressing at 10 MPa. Different firing temperatures, 800, 900 and 1000 °C, were studied. The fired bricks with high volume ratio of fly ash present a high compressive strength and a low water absorption capacity. With increase in firing temperature, the compressive strength increased and the water absorption decreased. With increase in replacing ratio, the compressive strength decreased and the water absorption ratio increased. The bricks no present environmental problems according to the leaching study.
TL;DR: In this paper, two samples waste linter (W Linter) and tablecloth (W T ) were produced by shredding and mixing, and thermal conductivity and diffusivity were determined by means of the box method equipped with a flash.
Abstract: A recycled textile materials were thermo physically characterized in terms of thermal conductivity and diffusivity. Two samples waste linter (W L ) and tablecloth (W T ) were produced by shredding and mixing. Thermal conductivity and diffusivity were experimentally determined by means of the Box Method equipped with a flash. The Parker equation and Degiovanni equation were used to evaluate the thermal diffusivity. Studied properties were compared to other usual building insulating materials. Results show that the thermal conductivity of W T and W L were 0.033 W/mK and 0.039 W/mK, respectively. In addition, the thermal diffusivity was found to be about 5.8×10 −3 m 2 /h in the case of W T and about 3.8 m 2 /h·10 −3 for W L sample. Therefore, the recycled textile materials have competitive thermal properties and could be used in the building insulations materials.
TL;DR: In this article, a new modular system for vegetated surfaces has been developed to create more sustainable green roofs and green walls, which can protect building envelope from surrounding environment while contributing to improve buildings design and thermal performance.
Abstract: Green walls can protect building envelope from surrounding environment while contributing to improve buildings design and thermal performance. The design concept of a new modular system (Geogreen) for vegetated surfaces has been developed to create more sustainable green roofs and green walls. This paper aims to present the study of Geogreen system thermal performance in a Mediterranean climate. This work is based on the evaluation of local meteorological conditions in three different periods. The Geogreen system is tested in an exterior test cell, comprising a reference wall and a wall covered with Geogreen modules. The analysis is based in the interior surface temperatures and interior surface heat fluxes of two compartments with the same dimensions and thermal characteristics. Resuts show that Geogreen system contributes to: reduce maximum interior surface temperatures and increase minimum interior surface temperatures up to 7 °C; mitigate heat transfer, reducing maximum income heat flux by 75% and maximum outgoing heat flux by 60%; enhance thermal insulation of a wall; and increase thermal delay between the exterior and the interior. These aspects can lead to reduce and shift air-conditioning power loads and to improve buildings thermal performance.
TL;DR: In this article, the most important 35 standards are reviewed and a correlation between activity in standard generation and completed buildings is presented, and a consideration of the proportion of humanity that live in countries without any standards and the ratio of new-build activity vs. pre-existing stock, leads to a conclusion that there is an urgent need for a binding international zero (rather than low) energy/carbon standard that can be adopted worldwide.
Abstract: There are in excess of 70 low or zero energy/carbon building definitions/standards in circulation around the world. However there are few zero energy or zero carbon buildings. This suggests that despite, or possibly because of, a continuing debate over definitions, aspiration has not been met by reality. In this paper the most important 35 standards are reviewed and a correlation between activity in standard generation and completed buildings is presented. Combining this with the requirement for an 80% cut in carbon emissions, a consideration of the proportion of humanity that live in countries without any standards and the ratio of new-build activity vs. pre-existing stock, leads to a conclusion that there is an urgent need for a binding international zero (rather than low) energy/carbon standard that can be adopted world-wide. It is argued this is only possible if carbon is ignored in favour of energy, and many lifecycle issues put to one side. In part this is because of changing national carbon intensities within the energy supply chain, but it is also due to unresolved issues in carbon and energy accountancy. It is hence suggested that such issues are left to optional additional local standards.
TL;DR: In this article, the influence of water, acid and alkali aging solutions on the durability and on the mechanical strength of basalt fibers reinforced polymer (BFRP) rods was verified.
Abstract: Basalt is a common material used in constructions since antiquity. Nowadays its fibers (BFs) are going to be used as an alternative to glass, carbon or aramid fibers for strengthening purposes in building engineering. In particular, the use of basalt ropes on historic masonries seems to be a good solution to give them a monolithic behavior. Besides, basalt fibers reinforced polymer (BFRP) rods have emerged as a possible solution to the corrosion problems of steel reinforcement in reinforced concrete for new or damaged structures or to the strengthening of historic masonries by repointing. Anyway, there is till a lack of knowledge about their durability. Thus this paper presents durability tests performed on BF ropes and BFRP rods. The influence of water, acid and alkali aging solutions on the durability and on the mechanical strength of them was verified. In order to increase the durability in alkali environments (i.e.: concrete), a PMMA coating was also applied on the BFRP rods and its effect was assessed too. Results show that alkali environments could seriously affect the durability of BF ropes and BFRP rods, thus a suitable coating should be provided to protect them before their use on such environments.
TL;DR: In this article, the authors used the Enhanced Response Surface Method (RSM) to present the most significant factors affecting the chloride diffusion at different ages, such as water-to-binder (W/B), metakaolin replacement (MK), and total binder content (350-600 kg/m 3 ).
Abstract: Chloride diffusion coefficient depends on many variables including concrete quality, environmental conditions, and time. In this investigation, the concrete quality and time were studied while maintaining the environmental conditions constant. Fifty-three concrete mixtures were tested based on a refined statistical analysis. Enhanced response surface method (RSM) was used to present the most significant factors affecting the chloride diffusion at different ages. The tested mixtures contained various water-to-binder (W/B) (ratios 0.3–0.5), metakaolin (MK) replacement (0–25%), and total binder content (350–600 kg/m 3 ). Bulk diffusion test was adopted for two years to determine the time-dependent coefficient m of chloride diffusion for all mixtures based on the error function solution to Fick's law. This coefficient was calculated based on two different bulk diffusion test methods: total and average methods. Design charts were developed to facilitate the optimization of mixture proportions for designers/engineers. The investigation also included some experimental relationships between the rapid chloride permeability test (RCPT), chloride diffusion coefficient, and compressive strength results. The results showed that the values of the chloride diffusion indicated a general reduction from 28 days to 760 days of testing. As the percentage of MK or binder content increased or as the W/B ratio decrease, the chloride diffusion reduction coefficients, m total and m avr , were found to increase. Based on the analysis of variance (ANOVA) from the statistical model, MK was found to be the most significant factor affecting the chloride diffusion at late ages (360 and 720 days), while the W/B ratio was the most significant factor affecting early ages of chloride diffusion (28 and 90 days). The developed models and design charts in this paper can be of special interest to designers/engineers by aiding prediction of service life of concrete containing MK.
TL;DR: In this paper, the results showed that the fired bodies of the mixture composed of 50% by mass of kaolin, 20% bymass of talc and 30% by of mass of bauxite together with high sintering temperature (1400°C) resulted in the formation of abundant amount of cordierite in conjunction with mullite, cristobalite and pseudorutile.
Abstract: Cordierite (2MgO·2Al2O3·5SiO2) is a thermal resistant ceramic presenting both low thermal expansion and electrical conductivity along with good chemical and mechanical properties. Thereby, it is suitable as material for manufacturing electric insulators, catalysis, refractory and porous ceramics. Solid-state reaction is the most common method for cordierite preparation. For this purpose, different mixtures including clay, alumina, talc, sand, diatomite and gibbsite are used. The present study is devoted to the preparation of cordierite-based materials using two mixtures of kaolin, talc and bauxite. Hence, prismatic specimens were shaped and tested to uniaxial compressive strength and heated in the range of 1200–1400 °C. The fired specimens were investigated via X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. Also, physical (firing shrinkage, water absorption, bulk density) and mechanical (bending strength) and dielectric properties of the fired bodies were measured as a function of temperature. The results showed that the fired bodies of the mixture composed of 50% by mass of kaolin, 20% by mass of talc and 30% by of mass of bauxite together with high sintering temperature (1400 °C) resulted in the formation of abundant amount of cordierite in conjunction with mullite, cristobalite and pseudorutile. Also, there was increase of firing shrinkage, bulk density and bending strength. These changes were essentially linked to amount of new phases that were formed. Water absorption declined with increase of sintering temperature which was related to the reduction of porosity due to the formation of vitreous phase. The mixtures of kaolin-talc-bauxite which were fired at the range of 1300–1400 °C exhibited dielectric constant values varying between 20.3 and 2.8 along with dielectric loss tangent which varied between 0.1316 and 0.0002 at room temperature of the laboratory. The two mixtures can be considered as promising materials for both ceramic and electronic applications.
TL;DR: In this paper, insulation materials containing waste olive seeds, ground PVC, wood chips, plaster and epoxy were produced, and their properties were investigated, including unit weight, water absorption rate, ultrasonic penetration velocity, thermal conductivity coefficient, compressive and flexure strengths properties of the samples were determined.
Abstract: The waste of the olive oil production process has been a notably important pollution source in Mediterranean countries, such as Italy, Spain, Greece, and Turkey. In recent years, the environmental impact of this type of waste created a rich source, and researchers have been focusing on the treatment of olive oil mill waste. Furthermore, olive seed, waste PVC and wood chips are wastes that cause significant detrimental effects on the environment, following the production stage. In this study, insulation materials containing waste olive seeds, ground PVC, wood chips, plaster and epoxy were produced, and their properties were investigated. The unit weight, water absorption rate, ultrasonic penetration velocity, thermal conductivity coefficient, compressive and flexure strengths properties of the samples were determined. It can be seen from the results that most properties have improved with the addition of the additives, The unit weights of the samples and their thermal conductivity coefficients decreased, thanks to olive seeds, PVC and wood chips. However, the decrease in the unit weight was accompanied by an increase in the water absorption and a decrease in the flexural and compressive strengths of the samples, luckily remaining at acceptable levels for the additive rates in the samples.